The present invention relates to method and apparatus for manipulating or enhancing the image signal that is provided by a document scanner or other image capturing device. More specifically, the invention provides operator control and enhancement of the digital image signal that results from a document scanning process or apparatus. Further, the present invention may be used with copiers, and/or printer-copiers which also provide a digital image signal.
In a conventional scanner a document is scanned to create a digital representation of the document. One such method and apparatus for scanning is described in U.S. Pat. No. 4,937,682. The scanning process converts the visual image of the document into a digital image signal. The digital image signal can be used in many ways, for example, the image signal can be transmitted to remote locations for storage or for reproduction by a printer, or the image signal can be manipulated in a manner to enhance or change the image, or the image can be merged with other images.
One problem associated with the document scanning process is that the initial scan of a document usually does not result in the preferred appearance of the image of the scanned document. Documents which present particular difficulties for scanning comprise a black image and/or shades of gray on a white background. More generally, the document image may comprise colored line text images, and/or color-scale pictorial images on a different color background substrate, such as paper.
The appearance of the scanned image depends on a variety of scanning parameters, such as density, contrast, focus, or other physical aspects of the scanning process. In addition, the appearance of the image may further be dependent on image processing functions such as edge enhancement, gamma correction, or other algorithmic manipulations of the raw image data. Usually, users of the scanning apparatus wish to adjust the scanning parameters and/or the image processing functions to obtain the preferred appearance of the image.
However, the conventional method for optimizing these parameters is slow and tedious. A conventional scanning apparatus typically displays the results of an initial scan on a video display. Such a prior art video display is depicted in FIG. 2. The display 16a shows the image 30, together with the values of one or more scanning and/or image processing parameters, shown as bar graphs 32, 34, 36, and 38. After viewing the display of an initial scan, the user typically adjusts one or more of these parameters, and then re-scans the image. Alternatively, the change in parameter may be affected through digital processing. In either case, a second appearance of the image is presented based on the change in the parameter value(s). After viewing the results of the second scan, the user may then continue attempting to optimize the appearance of the image by adjusting the parameter values until a final set of parameter values is selected.
This method of selecting parameter values to produce the preferred image results in a wasteful trial-and-error method of attempting to find the best combination of many different parameter values. For example, the selection of the optimal combination of values for the parameters of contrast and density for an image can be tedious and time consuming. The initial scan uses initial values for the contrast and density parameters. The initial display of the scanned image shows the appearance of the image based upon the initial contrast and density values. The value of the contrast parameter may then be changed, and a resulting new appearance may be displayed after scanning. Changes to the value of the contrast parameter, however, may require changes to the value of the density parameter to optimize the appearance of the image. Thus, the value of the density parameter may then be changed, and a third appearance may be displayed after scanning. This change to the value of the density parameter may require another change to the value of the contrast parameter, to again determine whether the appearance of the image is optimal after scanning. Thus, attempting to select the optimal combination of values for the contrast and density parameters may involve many different selections of different combinations of values for these parameters in an attempt to find the optimal appearance.
What is desired, therefore, is a system by which the user may be quickly presented with the results of variations in the adjustment of the image parameters, and by which the user may subjectively select a particular set or sets of adjustments to these parameters.
The present invention takes the form of a method for image processing. An image is scanned or otherwise acquired and a first portion of the image is displayed based at least in part upon a first value of a first adjustable parameter, where the first parameter affects the appearance of the image. A second portion of the image is simultaneously displayed based at least in part upon a second value of the first parameter, where the second value is different from the first value. A first processing value is selected based upon at least one of the first value and second value. The image is then processed in accordance with the first processing value.
In the preferred embodiment, the first portion of the image is displayed adjacent to the second portion of the image. Also, the first parameter is selected from the group consisting of density, contrast, focus, edge enhancement, and gamma correction.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.